The Neural Mechanistic Understanding Of The Influence Of Stress On Motor Performance Of Precision Sports

There is a causal relationship between brain activation state and motor performance.The study of the neural mechanism of stress affecting sports performance is one of the hotspots in the current sports field.Existing stress studies have consistently found that under pressure unnecessary brain activation increases and nerve efficiency decreases,but this change in brain activation does not bring inevitable changes in behavior.The neural mechanism of stress affecting motor performance is still unclear.Clarifying the brain mechanism of stress affecting motor performance can help athletes and coaches understand stress,and seek the interventions to prevent"Choking"from the perspective of neuroscience.Cascade model of cognitive-affective motor neuroscience proposes that the performer's perception and appraisal of stress environment will induce different brain activations,which will have different effects on action output.When the performer evaluates a stress event as an opportunity,the left prefrontal cortex will be activated,which will promote moderate brain activation,efficiently recruit motor neurons,and promote motor performance;when stress event is evaluated as a threat,it will induce excessive activation of the amygdala,enlarge neural noise,excessively recruit motor neurons which will affect motor output and motor performance.This model provides new research ideas for stress research,but the scientificity of the model has not yet been confirmed,and further verification is needed.The multi-action plan(MAP)model controls the cognitive processing state variables in the action execution process when comparing the brain activation characteristics of good motor performance with that of bad motor performance,and it turns out that cognitive processing state had a mediating effect on the relationship between brain activation and motor performance.Brain,under automatic processing,has low brain activity and high neurological efficiency;under controlled processing,brain achieves optimal performance via reasonable allocation the investment of resources.The unreasonable brain allocation of reinvested resources in the controlled processing state will induce dysfunction and affect the action output,but the symbols for judging whether the resource allocation is reasonable or not are still unclear.Moreover,stressful environments will destroy the homeostasis of the human body.In order to maintain the homeostasis,the body will inevitably invest brain resources to increase participation in control processing.Exploring the impact of stress on cognitive control and the characteristics of neural activity,it is very important for exploring the key brain wave characteristics that affect sports performance in the state of control processing.Searching the key brain features which affect sports performance under controlled processing has important practical significance for clarifying the brain mechanism under the pressure.This study is based on the cascade model of cognitive-affective motor neuroscience and the MAP model,with undergraduate as object,and the1-back task and the dart task as the research tasks,to explore the neural mechanism of pressure affecting sports performance by comparing the effects of different results of stress appraisal on cognitive control and dart performance.The research includes 1 cognitive study and 3 studies about dart.Study 1 explored the impact of stress on cognitive control based on the MAP model.According to the cascade model of cognitive-affective motor neuroscience,we set up the opportunity pressure situation,which induced objects to re-evaluate the stress with opportunity,and the threat pressure situation,which induced objects to re-evaluate the stress with threat.the research used 1-back task and adopt the in-subject design.The experiment 1 recruited 30undergraduates to perform 1-back tasks under three pressures situation:no pressure,opportunity pressure,and threat pressure,and collected their EEG signals.the data of 1-back were divided into4 different sequence types according to the sequence of 3 trials in a row:1)Repeating the same stimulus three times(named as RR;including???and???);2)Repeating the same stimulus twice followed by a different stimulus,(named as RA;including???and???);3)Altering the stimulus in the first two followed by repeating the second stimulus on the third(named as AR;including???and???);4)Altering the stimuli twice in the three trials(named as AA;including???and???);then draw an ERP diagram based on the event-related potential A 3×4(Pressure×Sequence types)two-way repeated-measures ANOVA was employed to examine the effects of pressure and interference on cognitive control and on ERP(Event-related Potentials)components.The data of feeling showed that the somatic anxiety under the opportunity pressure was significantly lower than under the threat pressure(p<.05);under threat pressure,subjects had more worry on teammates'disappointment(p<.05),and had highest pressure perception(p<.05).The results of performance showed that the main effect of the sequence type was significant(p<.05),and there were significant differences between each sequence type.Among them,RR had the shortest response time and the highest accuracy,and AA sequence had the longest response time and the lowest accuracy.The main effect of pressure was significant at reaction time(p<.05),and the response time under threat pressure was significantly shorter than no pressure;the interaction between pressure and sequence type was significant(p<.05).The simple effect analysis showed that the response time of RR sequence under opportunistic pressure was shorter than that of other two situations;the response time of the AA sequence under threat pressure was significantly shorter than that of other two situations;the accuracy of the AA sequence under threat pressure was significantly higher than the that of opportunity pressure.The results of ERP data showed that the main effect of pressure in the early ERP components including P1 and N1was significant(p<.05);under opportunity pressure,P1,N1 on occipital and on frontal and and N1on prefrontal had significant amplitudes,especially in the left hemisphere;Sequence type has a significant effect on the later components including N2 and P3,but the impact on different brain regions was different;the interaction between pressure and sequence on the central regions were significant(p<.05).Under threat pressure,the AA sequence's N1 amplitude on C3 was significantly smaller than opportunity pressure;under threat pressure,the RA sequence's P3amplitude on C4 was significantly higher than the other two conditions.The results of experiment3 showed that stress appraisal has a selective effect on the cognitive control system.The dependence of proactive control under opportunity pressure was enhanced,on the contrary,threat pressure enhanced the bias of response control.Study 2 was a pre-experiment,with the purpose of exploring effective stress situations that could affect sports performance.It contained 2 experiments.Study 2 took darts as the research task and 21 undergraduates as object.Experiment 2 required the subjects to throw darts in five situations including small prize,big prize,small punishment,big punishment and no pressure.and compared the dart performance and subjective feelings under 5 situations.The results showed that big prizes and big losses brough greater cognitive anxiety(p<.05)and less self-confidence(p<.05),but due to the large differences between individuals,there is no difference in post-hoc test showing that individuals had different stress appraisal for the same stress event.Participants had better performance under the small prizes condition(p<.05).Experiment 3 required the subjects to throw darts under four pressure situations including competition,camera,spectator,and no pressure and compared the performance and subjective feelings under 4 pressure situations.The results showed that there was no significant difference,but different public pressure situations had different directional effects on the performance of novice darts.The influence of competitive on sports performance showed a tendency to damage,while the influence of camera and spectator pressure on sports performance showed a promotion trend.The results of the study 2 showed that setting personalized goals in the novice group was very important for guiding subjects to have similar appraisal.Setting the real loss pressure had difficulties and need to be applied cautiously.The social evaluation pressure brought by competition could be integrated with other forms of pressure.Study 3 was based on the cascade model of cognitive-affective motor neuroscience to explore the effects of different pressure appraisal on the performance of novice darts and their neural activity characteristics.Experiment 4 recruited 17 undergraduates to throw darts under three pressure conditions including no pressure,opportunity pressure,and threat pressure,and collected their EEG signals and self-evaluated reports about processing state during throwing dart.The short-time Fourier transform was used to perform time-frequency analysis on the EEG data from 1800 ms before releasing dart to 200 ms after releasing dart.And then the EEG data of 1400ms before releasing dart was divided into 7 equal segments.The 3(pressure)×7(time)repeated ANOVA was used to analysis the power of?wave(4-7 Hz),low-frequency?wave(7.5-10 Hz),high-frequency?wave(10.5-13 Hz),which were from 17 poles including Fp1,Fp2,F3,Fz,F4,Fc1,Fc2,C3,Cz,C4,P3,Pz,P4,O1,O2,T7,T8.The subjective feeling data showed that threaten stress induced higher stress perception and cognitive anxiety.The result of behavior data showed that the motor stability of novice and pressure perception were in an inverted U curve relationship.The total variation under opportunity pressure was significantly lower than no pressure(p<.05),and the variation error was significantly lower than other two(p<.05).The results of EEG time-frequency data showed that the main effects of pressure ware significant on the power of high-frequency alpha on T7 and on the power of high-frequency alpha(?₂)on O1 and on the power of low-frequency alpha(?₁)on O1(p<.05).Under threat pressure,the power of?₂ on T7and the power of?₁ on O1 were higher than no pressure.Under no pressure,the power of?₂ on O1 was lower than other two situations.A separate analysis of the data of controlled processing darts showed that the result trend of dart behavior data and EEG data was consistent with the total data.Comparing with the total data,the pressure effect of the power of?₁on O1 was not significant,while the pressure effect of the power of?₂on O1 was increased(p<.01).Study 4 was based on the MAP model to explore the neural mechanism of the influence of stress on motor performance under controlled processing.In experiment 4,14 male undergraduates were induced to use controlled processing to throw 40 darts under the threat pressure.The data of EEG were divided into good or bad two types according to the performance of dart.And then the EEG data of 1400 ms before releasing dart was divided into 7equal segments.The 2(performance)×7(time)repeated ANOVA was used to analysis the power of three waves,including?,?_1,?₂,on 17 poles and the power of Mu rhythm(8-13)and SMR(12-15 Hz)at the Cz.The results of time-frequency data showed that the difference of?power on O1 was observed between good trials and had trials,the power of good trials was higher than bad trials(p<.05).This study had the following conclusions through the above 4 studies and 5 experimental results.1)Different stress appraisal has different effects on cognitive control and sports performance.2)Different stress appraisal has selective influence on cognitive control system.If the stress is re-evaluated to an opportunity,the stress would increase the dependence of the brain on proactive control;If the stress is re-evaluated to a threat,the stress would increase the bias in response control.Stress affectes performance by affecting cognitive flexibility.When stress induce the bias on cognitive control is correspond with task requirements and environmental changes,it would promote performance,and vice versa.3)Opportunity pressure can effectively promote the stability of novice action output,while threat pressure has a tendency to impair novice action stability.4)Under the pressure,novices inhibit semantic processing and visual information processing to integrate resources.Opportunity pressure can promote the novices'motor stability by effectively inhibiting visual information processing.5)Under threatening pressure,the body through maintains a high left occipital lobe?wave power to maintain a stable motion output under a situation where the control processing is highly involved.6)The characteristics of brain nerve activity in the left occipital lobe should be the main focus of future stress research.